Viscometer



J. D. FANN Jan. 15, 1963 VISCOMETER 5 Sheets-Sheet 1 Filed Dec. 3, 1959fairies @fazzzz Filed Dec. 3, 1959 Jan. 15, 1963 J. D. FANN 3,073,150

VISCOMETER 5 Sheets-Sheet 2 FIEE J.D.FANN

VISCOMETER Jan. 15, 1963 5 Sheets-Sheet 3 Filed Dec. 5, 1959 N mm ww J.D. FANN Jan. 15, 1963 VISCOMETER 5 Sheets-Sheet 4 Filed Dec. 3, 1959ZIZZ/IZ-ZOW.

Japzes Far? J. D. FANN Jan. 15, 1963 VISCOMETER 5 Sheets-Sheet 5 FiledDec. 3, 1959 United States Patent 3,073,150 VISCOMETER James D. Fann,Houston, Tex., assignor to Great Lakes Carbon Corporation, New York,N.Y., a corporation of Delaware Filed Dec. 3, 1959, Ser. No. 856,962 17Claims. (Cl. 73-954) This invention relates to a device for measuringthe consistency or viscosity of fluids. More particularly, thisinvention relates to a device for measuring the consistency or viscositycharacteristics of fluids at, diflerent pressures and temperatures, andis particularly adaptable to measuring the changes in consistencies orviscosities of fluids which undergo a chemical reaction or physicalchange depending upon the pressure and temperature of the fluid, or onchanges in the pressure and temperature, or on the length of time thatthe fluid is subjected to different or varying pressures and/ortemperatures.

While the present invention is not so limited, it is particularly welladapted to measuring the viscosity characteristics of fluid materialscommonly used in the oil and gas industry. In connection with thedrilling of oil and gas wells, a variety of fluid compositions aresubjected to elevated pressures and temperatures which occasionaly causerapid increases in the viscosity of such fluid compositions which arepumped into the Well bores. In the completion of such wells, it iscommon practice to pump a cementitious slurry down into the well throughcasing, and force this slurry up through the annulus between the casingand the well bore. This operation is designed to seal off the overlyingformations from the oil or gas producing zone with set cement. It iscommon knowledge that aslurry of Portland cement, with or withoutaggregates or other additives contained therein, tends to thicken andoccasionally flash set in the well in a relatively short period of time.The deeper the well, the higher generally will be the temperature andpressure to which the cement slurry is subjected and thesev conditionsaggravate the setting problem.

In view of the foregoing facts, there has been a great need for a deviceor an apparatus and a method capable of measuring the changes inviscosities of Portland cement, slurries and other fluids which will besubjected to varying temperature and pressure conditions in wells, aswell as, or alternatively capable of measuring the time intervalsrequired to reach various consistencies or viscosities under variedtemperature and pressure conditions. These conditions may, for example,vary from atmospheric pressure to eighteen thousand lbs/sq. inch andfrom 80 to. 400 F. To accomplish the foregoing objectives it is de-.sirable to simulate well conditions as closely as possible. A typicaltime-pressure-temperature well-simulation schedule for cementing casingfor a 14,000 foot well is as follows:

Time (Min.)

Pressure Temperature (p.s. i.) F.)

6, 760 134 7, 040 137 7, 320, 140 7, 600 143 7, 880 14s 8. 160 149- 8,440 152 8, 710 155. 8, 990 158 9, 270 161 9, 550 164 9, 830 167 10, 110170 10. 300 173 10, 670 176 10, 950 179 11, 230 182 185 11, 780 188 12,one 191 40. 9 12, 620 197 900 200 13, 180 203 13,390 206 The instrumentherein described is suitably adapted to closely simulate the foregoingtime-pressure-temperature. schedule as well as similar schedules.

Certain forms of apparatus have been devised by others to measure thechanges in viscosity or consistency of Portland cement slurries undercontrolled time-pressuretemperature conditions. These devices generally,how. ever, are very expensive and physically quite cumbersome. They arenormally retained in regional laboratories where consistency tests aremade, It is, however, desirable to. have a portable consistometer whichcan satisfy the foregoing needs and which can be used on the well siteto measure what the viscosity characteristics of cement slurry samplestaken directly from cement trucks just prior to the pumping of thecement slurry into the well for cementing casing are likely to be.

The devices which have heretofore been used for testing cements, besidespossessing the aforedescribed shortcomings, are further provided withpaddles, agitators or similar means which continuously stir the cementslurry or other well fuid in the testing apparatus over a desiredtime-pressure-temperature testing cycle. When friable materials such aslightweight aggregates which are often used for lowering the weight ofcement slurry and/ or for sealing or bridging ofl certain areas in thesubterranean formation are incorporated into the cement slurry, theseinternal mixing devices tend to degrade or abrade such materialsand'this will affect the viscosity and setting time of the cementslurry. Therefore, conventional laboratory devices currently in usecannot give a truly accurate prediction ofthe viscosity changes, andthetimes required for same for cement-aggregate slurries under actualwell conditions.

The apparatus of the present invention is also adaptable for generalstudies of changes in viscosity of, oil well drilling fluids undervarying conditions of pressure and temperature. It isalso useful in thetesting of fluid compositions which are not necessarily connected withthe drilling and completion of oil and gas wells. For example, theapparatus of .the present invention .is adaptable to measuring theviscosities of such materials as lubricants,

whether these be of petroleum base or some other base material, liquidfoodstuifs such as syrups, molasses; anti freeze solutions, etc, and thetimes requiredfor viscosities of such materials tochange from onepredetermined value to another predetermined value at temperatures andpressures either above orbelow usually prevailing atmosphericconditions. i

fluids which are characterized by undergoing chemical or physicalreaction or change, depending upon changing conditions of time, pressureand temperature. It is a further object of the present invention toprovide an ap paratus or device as well as a method for measuring the atime intervals required to reach various viscosities of fluids which arecharacterized by undergoing chemical or physicalreaction or change,depending upon changing conditions of time, pressure and temperature.

It is a further object of the present invention to provide a devicewhich will achieve the foregoing objects with'fluids'which containfriable materials suspended therein and in which the degrading of suchmaterials is minimized or substantially eliminated. V

- Further objects and advantages of the present invention will beapparent from the following detailed description particularly whenconsidered in conjunction with the accompanying drawings. i

7 FIGURE 1 shows a perspective view of the fluid receiving vessel andassociated elements employed in the present invention with most of thefeatures shown in cross-section, and certain other features beingrepresented schematically or diagrammatically.

FIGURE 2 shows a partial viewv of the device shown in FIGURE 1', butmodified by the omission of the lower coil and therefore showing analternative but generally less preferable device for carrying out theteachings of this invention.

FIGURE 3 is a partial cross-sectional view taken along the lines 3-3 ofFIGURE 1 showing the pressure supply. means and associated features ingreater detail than is shown in FIGURE 1.

[FIGURES 4 and 4A show a schematic diagram of the electrical circuitsand various associated mechanical elements which complement the fluidreceiving vessel of the present invention.

FIGURES. shows a block diagram of the electrical circuitsand variousassociated mechanical elements shown in FIGURES 4 and 4A. 4 1

In a broad embodiment the invention comprises a substantiallynon-magnetic container for the fluid to be tested, an electromagneticwinding surrounding a defined area or portion of the cavity or well ofsaid container for establishing a magnetic field in said portion of saidcontainer, meanshaving an appreciable viscous. drag and being responsive. to said magnetic field positioned within said container and freelymovable in the fluid, means for intermittently and regularly energizingsaid windingwhereby said electromagnetically responsive movable means iscaused to move into the resultant magnetic field, surfaces at both thetop and bottom of. said defined area of said container which generateand transmit sound waves when struck by said movable means, and meansresponsive to the generated sound waves from which the consistency orviscosity of the fluid in said container may be determined. at any giventime, or from which the time required for the consis t encyor.viscosityof the fluid to change from one value to anotherpredetermined value may be obtained.-

'-In a preferred embodiment the invention comprises a substantiallynon-magnetic cylindrical container for the fluid to be tested,electromagnetic windings surrounding upper and lower portions'of acavity orwell in said container for establishing magnetic fields in saidportions of said c'ontainer, means having an appreciable viscous dragand being responsive to said fields positioned within-saidco'ntai'nerfand'freelymovable'in .thezfluid, means for inttermittentlyand. regularly electrically energizing said windings .whereby'. saidelectromagnetically responsive movablemeans is caused to move into the.resultant respective magnetic fields and move toward the top and bottomsurfaces of the cavity of said container, surfaces at both the top andbottom of said cavity which generate and transmit sound waves whenstruck by said movable means, means for converting said sound waves intoelectrical signals, means for amplifying said electrical signals, meansfor sensing variations in the viscosity of the fluid as the viscositychanges from one value to another predetermined value, electronic meansfor energizing the upper and lower electromagnetic windings tied in withor associated with the viscosity variations sensing means and means forrecording when such predetermined viscosity variations occur.

The foregoing-described broad and preferred embodiments of thepresentinvention will also become better understood after the attached drawingsare studied in detail.

Referring therefore to the drawings and particularly FIGURE 1, there isshown a pressure cell or container 1 which is constructed .of anon-magnetic material capable of withstanding high pressures and alsocapable of conducting sound and heat. Stainless steel, brass and Monelmetal are typical satisfactory materials. The container is providedwitha fluid-tight, sound-conductive pressurewithstanding plug or closure2.. This plug or closure 2 is threaded into the top inner threaded,tapered part 3 of the container. The center of the plug or closure 2 ishollow and cylindrical in shape. A pressure inlet stem 7 e 4 made of amagnetic material extends through this hol low center of the plug. Thebottom 5 of the pressure inlet stem 4 is flanged. Between the top partof this flange and the bottom of the plug or closure 2 is placed asealing gasket 6 which may be made from a resilient andtemperature-resistant material such as Teflon. Teflon is a registeredtrademarkof the E. I. du Pont de Nemours Company for a plastic materialconsisting of a tetrafluorethylene polymer. A pressure seal nut 7 isthreaded around a threaded portion of the pressure inlet stem 4 untilthe upward motion of the flange 5 of the inlet stem causesthe sealinggasket 6 to form an initial pressure seal. Any further pressure exertedon the contents of the container or pressure cell then assists inkeeping the cell pressure tight for itsimply exerts more force on theflange against the gasket. placed between the' plug 2 and a seal nut 7to keep them separated and to keep them from locking. Situated withinthe cavity or well 9 of the container is a thermowell 1 0 in whichis-placed wires 10A of an electric thermometer for measuring thetemperature of the fluid placed within said central cavity 9. Thethermowell extends about halfway down into this main cavity or well ofthe container. Also situated within the main cavity 9 of the containeris an electromagnetically responsive iron plunger or bob 11 which iscylindrical in shape, but hollow at its center. The top 12 of this ironplunger or bob is preferably made from a non-magnetic material such asbrass. The iron plunger 11 during the operation of the device is causedto strike the top surface 13 of the main cavity of the container (whichis also the bottom of the flange 5 of the pressure inlet stem 4) as wellas the bottom surface 14. Both of these surfaces, being metallic,readily generate and transmit sound waves when struck by the bob.

- The top of? the pressure inlet stem 4 is threaded into.

a valve body 15. The'valve body 15 performs several functions. It servesas a coupling means between an external pressure line 16 and thepressure inlet stem 4. The pressure in this external pressure line,which line has its input or is coupled to the valve body 15 by means ofthreaded bolt '16A and nut 163, may be varied by a conventional handpump (not shown) acting on a fluid such as oil. A conventional pressuregauge (not shown) is also in the line to show'the pressure at any givenmoment. A gasket or' pressure packing 17, shown in FIGURE 3,

A bronze thrust washer 8 is Mechanically coupled to the valve body 15 bymeans of a thumb-screw clamp 22 is a pick-up transducer 23 which is amoving coil in a permanent magnet magnetic field tuned to approximately70 cycles per second.

Handle 24 may be turned to force the conical end of valve member 24B toseat into the opening of 24C in order to make the cell pressure tightbefore removing the external pressure line. This enables rapid coolingofthe cell if desired such as by immersion in water.

The pressure cell having the features and attachments as thusfardescribed is designed for ready insertion in an external chamber orhousing possessing several features. A shell or a can 25 immediatelysurrounds the side walls of the pressure cell. Immediatelysurroundingthe shell or can 25 is a means 26 for heating or cooling the contents ofthe pressure cell. Typically it may be a resistance wire heater. Theshell or can 25 may typically be made from a non-magnetic material suchas aluminum and serves to support the heating or cooling means and toplates 29 are at the top and bottom of each of these elec- I tromagnets.The cell 1 rests on a flanged soft iron base 30. Soft iron supportmember 31 extends upwardly from foregoing elements.

A specifically designed pressure cell has a main central cavity 1 /2 indiameter and '5" high. A soft iron bob 11, weighing about 500 grams,displacing 72 cc. of fluid and having an outside diameter of 1%" and /2"diameter central bore is placed in the cavity after about 76 'cc. of thefluid to be tested, such as cement, has been placed therein. This causesthe fluid being tested to rise to a height well above the top of themain cavity of the cell and insures that none of the :pressure'fluidwill getinto'the' main cavity. After all the closures and othermechani-jcal elements shown in FIGURES 1 and. 3 are properly coupled to the cell1 and valve body 15, a liquid, such as oil, substantially immisciblewith the fluid being tested, is then pumped into the system through thepressure input means 16 and the cell brought to the initially desiredpressure and temperature such as, for example 1750 p.s.i. and 80 F.required to start the test of the cement slurry.

In FIGURES 1 and 2 the cement slurry is marked X and the oil Z.

"In the system shown in FIGURE 1, the energizing of theftop 27 andbottom 28 electromagnets or coils sets up electromagnetic fields throughthe soft iron portions of the assemblage, including soft ironplates-29', the bob 11 and the flange 5 for the upper winding; and softiron plates 29, the bob 11. iron base 30 and support member 31 for thelower winding. The brass top 12 of the bobll prevents the bob fromsticking to the top surface of the cavity.

In the measurement of cementitious fluids such as are used in theoil-well industry, the attainment of viscosities of approximately 20, 70and 100 poises are recognized as being significant. j The arrival orobtainment of -a 20- 6 poise viscosity level generally requires the mosttime and also generally-indicates that the viscosity of the cement fromthat stage on will increase rapidly; the arrival at the poise levelsignals the upper pumpable viscosity point limit; and poise indicates anunpumpable material. To know when or how long or under what conditionsthese viscosities can be expected to be reached witha particular cementabout to be used is therefore very desirable for it will prevent theusing of a cement improper for the particular well conditionsencountered. This in turn will prevent needless effort and save muchtime and money by not using a cement which will prematurely set up.

Several factors or parameters are involved in the design of a pressurecell Whichwill successfully indicate when the cement reaches theseviscosity levels. These include the time cycles of the electromagnets,that is, how frequently they are energized and deengerized and for whatrespective lengths of time; the sample volume and dimensions of thecavity; the plunger shape, volume, weight and dimensions; and thestrengths. of the electromagnets and the relative forces exerted byeach. The electromagnetic forces exerted by the coils not only aredependent on how long the coils are energized, but depend, also on theirnumber of ampere turns and their magnetic circuits. These determinethe'fiux density which in turn'determine the respective forces theyexert on the plunger.

In-conjunction with the system shown in FIGURE 1 means are provided forenergizing either the top or bottom coil, or both, thirty times perminute with the top coil being energized for just under 1 secondeach'cycle and the bottom coil being energized for 1 second each cycle.The top and bottom coils possess approximately 5000 ampere turns. Withthis arrangement the top coil exerts approximately 1 gravitational pullof force less on the bob than does the bottom coil which is assisted bygravity. g I g The relatively blunt end shape of the bob asdistinguished from other possible shapes such as one with pointed ends,etc. is important to insure thorough circulation of the cement in thecavity as the bob goes up and down, and to therefore prevent spothardening of the cement leading to erroneous results.

From the foregoing detailed general description of the device it will beappreciated that there are several critical factors involved in thedesign of the device of the present invention.

The top surface 13 and the bottomsurface 14 of the cavity 9 of thecontainer are sound-responsive in nature, that is, they generate andtransmit sound whenever they are struck by the top or bottom,respectively, of iron plunger 11. The sound waves so emanating from saidsurfaces are picked up by the transducer 23. Sounds will be generatedonly'when iron plunger 11 is in motion and strikes either of theaforementioned surfaces. This motion placed in the container may be orbecome so great that the iron plunger cannot reach a particular strikingsurface of the cavity during a given time limit in the cycle. Thisfailure to reach astriking surface may be made a function of a measuredcalibrated viscosity, so that when such failure occurs-the operator thenknows that the fluid has reached a predetermined viscosity level. Thesepredetermined viscosity levels and Where they occur are discussed morefully hereinafter.

' It'will be noticed that the aforedescribed system is one whichprovides for easvcleaning after, any particular the system is one inwhich the desired pressures can easily be obtained. The temperatureWithin the container can similarly be easily altered, as will be morefully apparent after the remaining drawings have been described.Referring now to therassociated electrical elements and other parts oftheapparatus as shown in FIGURES 4 and 4A:

The transducer 23 converts the mechanical sounds made by the bob 11striking the upper and lower surfaces 13 and 14 into electrical signals.The transformer 33 serves as an impedance matching device between thetransducer 23 and the input of the amplifier circuit. The primary ofthis transformer is balanced and the center-tap grounded to reduceelectrostatic and electromagnetic pickup in the transducer andconnecting cable. The transistors 34 and 35, together with theirassociated components, form a conventional two stageclass A amplifier.Resistors 36 and 37'are. for'bias stabilization and resistors 38 and 39are load resistors forthe transistors. Blocking capacitors 40 and 41 aresmallenough to attenuate signals lower than the design; frequencycenter. I Voltage regulator diode 42 and resistor 43 serve to maintain aconstant supply voltage. for the two amplifier stages. They alsodecouple thearnplifier stages from other circuitry.

- ."The combination of'capacitors 44 and 45, resistors 46 and 47, anddiode 48 form a rectifier circuit which converts any continuous signalsuch as mechanical vibrationfelectrical interference or noise into 'aD.C. signal across capacitor 45.. This D.C. signal is blocked from 'thesubsequent circuitry by capacitor 49. Capacitor 44 is much larger thancapacitor so'that the maximum of any signal at the collector junction 50of transistor. 35

will appear across capacitor 45. The resultant capacity through.the'base junction by resistor 54 being returned to the supply voltage;The saturation current through the collector of transistor 52 and loadresistor 55 cause the voltage at point 56 to be very nearly zero withrespect to the common" ground 57. The base of transistor 51 is tied tojunction 56 through resistor 58. Therefore very little collector currentis flowing through transistor 51-and resistor 59 and the'voltage at thejunction 60 of these two is' very nearly equal to the supply voltage 61.Transistor During the cycle of operation-there appears at-junction 56 arectangular pulse of constant amplitude and constant width. Theamplitude is held by maintaining the supply voltage constant with thevoltage regulator diode 63 and. resistor 64, and the width is determinedby the time constant of capacitor 62 and resistor 54. This rectangularwave form will appear at junction 56 once for every discontinuous signalgenerated by the transducer when the time interval between signals isgreater than the pulse width.

When the rectangular pulse appears at junction 56, it also appears atrelay armature contact 65, normally closed relay contact 66 and at thebase connection of transistor 67. This causes heavy surge current-toflow through transistor 67, charging capacitor 68, which in turn startscharging capacitor 6? through resistor 70. When the charge acrosscapacitor 69 ha increased sufficiently, enough current will flow throughtransistor 71 and relaycoil 72 to move the armature contact A to thenormally open position 73. The values of capacitors 63 and 69 andresistor are chosen so that the relay '72 will-not operate until therectangular pulse at junction 56 has disappeared. The relay willremainclosed until the charges on capacitors 65 and 69 have decreased to thepoint where insufficient current is flowing through relay 72 andtransistor 71 to hold the'armature contact 65 down. The length of timethe relay 7?; stays energized can be adjusted by variable resistor 74.

At the same time capacitor 68 is charged, capacitor 75 is chargedthrough diode 76. This causes current to flow through transistor 77 andrelay coil 78". There is no delay in energizing relay coil '78. Theresistor 7? is for limiting the base current in transistor '77 to a safevalue. Relay coil 78 willstay energized for a much longer period than 53contributes very little to the total current through resister 59because: the base, connection is not returned to any fixed D.C.reference voltage. V a

. When a.discontinuous signal from the transducer appears at thejunction ofcapacitors 45, and 49, it will pass to the base :oftransistor 53v causing collector current 'to flow through transistor'53and resistor 59. This causes the voltage at junction 60 to decrease.As the voltage across the capacitor 62 cannot change instantaneously,the voltageat the junction of resistor'54 and the bElSG'COIl,

at junction 60; This action is regenerative and willcontinue'.until'transistorfsl is saturated and, transistor 52 is cutoil, Thecircuit will' stay in this state'until the chargeacrosscapacitor' 62 has been;re ducedby leakage through resistor 54 tothe point where transistor 52 can start conductionnAt thispointtheregenerative action is reversed and the circuit is returned to itsoriginal stable. state. i

relay coil 72 as the diode 76 has veryhigh back resistance, and variableresistor 74 has no effect on the time constant of capacitor 75 andresistor '79.

If a rectangular. pulse appears at junction 56 during the period whenrelay coil 72 is energized, it will pass through the relay armaturecontact 65, through the normally open contact 73 and vto the baseconnection of transistor 84). This will cause surgecurrent throughtransistor so to charge capacitor 31 which is connected to the base oftransistor 82 through resistor 83, thus causing currentto flow throughtransistor 82 energizing relay coil 84. The time constants here areessentially the same as those for transistor 77 and relay coil 78.

'If no-rectangular pulse appears at junction 56 during the time thatrelay coil 72 is energized, relay coil 84 will not become energized; orif relay coil 84 has previ ously been energized and no subsequent pulsesappear at unction 56during the time that relay coil 72 is energized,relay'coil 84 will de -energize when the charge across capacitorfil hasdecreased to a point toolow to maintin suificient current flow throughtransistor 32. Re-

' lay coil 78 will stay energized so long as any pulses at all nectionof transistor 52 decrease, thus decreasing the colappear at junction 56,

Voltage regulator diode 85 and resistor 86 maintain constant supplyvoltage so that peak charges on capacitor 68, 75 and 31 will beconstant. Capacitor 87 is very large to supply charging currents;

' One wire of the chartdrive motor S8 is connected to the operate switch89 and the other to the'normally open contact 90 of relay 73. Thearmature contact 91 is con- .nected to the common side of the power line92. With.

the operate switch'on and relay 78 energized the chart drive motor willrun. Whenjrelay 78 vie-energizes, the

' chart drive motor will stop and indicator lamp 93 will light throughrelay contact'94. "Also capacitor 95, which is'charged' throughrectifier 96 and resistor 97, will be discharged through relay contact93, 99, 106', 101, and I marker solenoid 192. f The marker solenoid willperforate the time chart'103.

Relay 78 will be energized so lo'ngas any pulses appear at junction 56.Relay$4 will be energized only if pulses ducer 23.

resistors.

Transformer 117, resistors 112, 113 capacitors 114, 115

and rectifier 116 comprise a half-wave rectifier to furnish power to thetransistor circuits. I

Bottom coil 28' is energized through relay contacts 113 and 119. Thelighting of neon lamp 120 indicates when the bottom coil is connected inthe timing circuit. Timer motor 121 is a 60 cycle 30 rpm. motor whichdrives a cam 122 directly. Cam 122 in turn moves thecenter arm ofmicroswitch123. Microswitch 123 alternates power once every second tothe top coil 27 and to the bottom coil 28 if the bottom coil is in thecircuit through relay contacts 118 and 119.

Capacitors 124 and 125 are filter capacitors for the top and bottomcoils respectively.

Capacitor 132, resistor 133 and bridge 1341 make up a bridge rectifiercircuit to furnish power to the top and bottom coils. 1

Heating elements 26 and a fan 131 are provided in order to heat or coolthe pressure cell, these being in the same insulated container as thecell.

Switch 135 which is placed on the face of the insulated chamber isemployed to turn the fan 131 on or oil as needed in order to keep thetemperature of the vessel as near ason' schedule as possible.

Switch 136, likewise on the face of the insulated cham- Fuse 139 isprovided for the top and bottomcoil power supply circuits. Fuse 140,switch 141 and neon lamp indicator 142 are provided for the amplifiercircuit. Resistor 143 is an impedance matching resistor for trans-Operation "123. During the other half of the cycle the microswitch 123is in position to energize the bottom coil 28, but the coil isdisconnected through relay 107. Therefore, once every two seconds thebob ll-is lifted and strikes the top 13' of the test chamber. Thismechanical sound is picked up by the transducer 23 and an electricalpulse appears at junction 56 as described before. This pulse energizesrelays 72 and 78. Relay 72 stays energized for a period of less-than 2seconds (approximately 1.85 seconds). One second after the top coil isenergized, it is de-energized and the hub falls to the bottom. The pulsefrom this sound then appears at. junction 56. However,

relay 78 is still energized and the pulse ,travels on to energizerelay84'. Relays 78 and 84 will stay closed for a period of about 15 to 20seconds with one pulse to each circuit. However, thebob is being pickedupand dropped one-second period during which the top coil is de-energized, the above condition will continue. When the cement slurrythickens to the point where the bob will not fall all the way to thebottom and strike the bottom surface before the top coil is energizedonce more, no pulse will appear at junction 56 when relay 72 isenergized and the charge on holding capacitor 81 will start decreasing.After about 15-20 seconds wherein the bob fails to strike the lowersurface, relay 84 will de-energize, discharging capacitor 104 throughthe marker solenoid 162 (which perforates the time chart 103) andenergizing relay 107. (In the system being described, this occurs whenthe cement being tested has reached a viscos ity of about 26 poises.)Relay contacts 119 and 110 then put the bottom coil in the timingcircuit. The bob will now be pulled to both top and bottom as the coilsare alternately energized. Relay 84 will'again become energized as thereis a pulse present at junction 56 during the time relay 72 is energized.Relay 107 will stay be no signal to operate relay 72. However, when thebottom coil is energized, the bob will be pulled back down and thesignal from the bob hitting the bottom will operate relay 72. There willthen be no signal to keep capacitor 81 charged so that in 15-20 secondsrelay 84 will again become de-energized causing the marker solenoid 102to perforate the chart again. (Inthe system being described this occurswhen the cement being tested has reached a viscosity of about poises).

As the samplethickens further, it-will reach a point where the bob isnot lifted off the bottom at all and there will be no signal to keepcapacitor charged. In 15-20 seconds relay 78 will become de-energized,discharging capacitor 25 through the marker solenoid 102 and perforatingthe chart. It will also stop the chart motor and light the indicatorlamp 93. This is the end of the test although for many purposes it willnot be necessary or desirable to carry the test this far.

FIGURE 5 shows a block diagram of the circuit shown in FIGURES 4 and 4Aand is set forth by way of explanation of the functions of theelectrical components of the system.

Descripti n of Block Diagram 'The 60-cycle'30 r.-p.m. motor 121 drivesthe cam 122 directly. The cam, in turn, moves the center arm of themicroswitch, 123 to its alternate positions once per second. Thus thetop coil 27 is energized'once every two seconds for a period of onesecond by the bridge rectifier 13 This lifts thebob through the slurrysample until it strikes the top of the sample container creating amechanical signal which is picked up by the transducer 23.

At the end of one second, the cam 122 moves thecenter arm of themicroswitch 123 to the opposite position, energizing the bottom coilonly if the bottom coillatching relay 107 is energized or the by-passswitch 107A for bot-tom coil 28 is closed, (The by -pass switch'107A isused only when testing slurry samples having an initial consistency toothick to allow the, bob 11 toreach the bottom of the 'container'in afree fall during the onesecond period whenithe top coil 27 isdeenergized.)

The fan 131, heaters 26 and heater control 138v are I used as needed tomaintain a desired temperature of the slurry sample or to changetemperature at a predetermined rate.

coil 27, allowing the bob'to fall.

11 13 of the container 9 is picked up by-the transducer 23, it is fedinto the circuitry, as aforedescribed, which make up the partsdesignated as the amplifier and wave-shaper ofFIGURE and appears atpoint A as a square wave pulse. This would be at point 56of FIGURE 4.This pulse is passed simultaneously through the relay contacts B and Cto the gating circuit and relay and to the holding circuit and relay forthe chart motor 88, causing the relay in'the latter circuit to becomeenergized, applying power. to the chart motor and removing power fromthe end of test indicator lamp 93. One pulse is sufficient to keeptherelay energized and motor 88 running for about lS .seconds. If noadditional pulses are received during this time, the relay willde-energize, motor 88 will stop, lamp 93 will come on, and a capacitorwill be discharged through marker solenoid .102 punching a hole in the.time chart.

, The gating circuit and relay 72 has av time delay which prevents thisrelay from 'operating'until after the pulse at point A has disappeared.It then energizes, moving the armature contact B to contact D thusconnecting point A with point I of the bottom coil and marker solenoidenergizing circuit. This relaywhich is relay 72 of FIG- URE 4 will. stayenergized for about 1 /2 seconds allowing sufiicienttimeforthe bob 11 tobe released by the top coil 27 'and fall tothe bottom of the container.The square wave created by the sound of the bob 11 striking the bottomnow appears at point I of the bottom coil and marker solenoid energizingcircuit. This is a holding circuit which prevents the bottomcoil-latching relay 107 from operating. If no pulses appear at point Ifor about seconds, the bottom coil latching relay will energize,connecting the bottom coil 28 to the microswitch'123, and

. a capacitor (95 of FIGURE 4A) Will be discharged through solenoid 102punching a hole in'the time chart.

The only way the bottom coil latching relay 107 can be deenergized is toturn the operate switch 89 off momentarily; v

A complete testing program consists of the following:

At time zero, the cam 122 operates the microswitch 123, energizing thetop coil 27. The bob 11 will be lifted through the slurry sample and atsome time betweentime zero and time 1 second (dependent upon thethickness of thesample) the bob'will strike the top of the container anda square-wave will appear at point A. This will cause the chart motor 83to start running and also initiate the action of the gating circuitrelay 72. After the square-wave has disappeared, the gating circuitrelay will energize, shifting the armature contact B to contactD. I 'Attime l second, the cam moves the microswitch center arm to the oppositeposition, de-energizing the top When it strikes the bottom of thecontainer, the resultantsquarewave Will appear at point J activatingthis holding circuit to prevent'the' bottom coil latching relay 107 fromoperating. 'At time 2 seconds, the top coil is again energized and theentire cycle is repeated.

' a The above sequence is repeated while the operator is changingthetemperature and: pressure in accordance withthe particular schedulebeing followed until the slurry sample thickens to a point where the bob11 will no longer fall -to the bottom during the l-second periodWhen-the top coil is off and no pulse will appear at point 7 J duringthetime the gating circuitrelay 72 is energized. Afterflabout 15secondshave'passed with no pulses appearing 'at point J, the bottom,coil' latching relay 107 will be energized connecting the bottom coil28 to the 'microswitch 123 and the solenoid 102 .will punch a hole inthe chart. This'represents a slurry sample consistency bob, its size,the strength of the electromagnets, etc.

Now, instead of the bob falling free whenthe top coil is oe-energized,it will be pulled' down by the bottom 1-2 coil .and again there will bepulses present at point A for each position of the gating circuit relay.This will continue until the sample further thickens to a point wherethe top coil can no longer lift the bob through it in the l-secondperiod the top coil is on. Then there will be no signal from the top toactuate the gating circuit relay, but the next signal from the bottomwill do so, and again no pulse will appear at point I. In about 15seconds, a capacitor will again be discharged through the solenoid 102punching another hole in the chart. This will occur at approximately 70poises in the system presently beingv described.

It the test is allowed to continue, the sample will the bob off thebottom and there will be no signals at all.

In about 15 seconds the relay that keeps the chart motor 88 running willde-energize, stopping the motor, turning on lamp 93 and another holewill be punched in the chart. It will, of course, be appreciated that'intesting several materials the test does not have to be carried this far,and that the arrivalat the 70-poise level or thereabouts will convey asuificieiit amount of desired infor' mation about the fluid beingtested.

Although I have described my invention in considerable detail, it isunderstood that the present disclosure has been made only by way ofexample and that numerous changes in the details of construction and thecombination and arrangement of parts, such as, for example, in the useof vacuum tubes rather than transistors, may be resorted to withoutdeparting from the'spirit and the scope of the invention as hereinafterclaimed.

I claim: I

1. An apparatususeful for measuring the viscosity characteristics of afluid whose viscosity changes under diiferent pressure and temperatureconditions comprising in combination a substantially non-magneticcontainer for the fluid, electromagnetic windings surrounding upper andlower portions ofa cavity in said container for establishing magneticfields in said portions of said, container, means having an appreciableviscous drag and being responsive to said fields poistioned within saidcavity and freely movable in the fluid, means for intermittentlyandregularly electrically energizing each of said windings whereby saidelectromagnetically responsive movable means is caused to move into theresultant magnetic fields, surfaces at both the top and bottom of thecavity of said container which generate and transmit sound waves whenstruck by said movable means, means for converting said sound waves intoelectrical signals, means for amplifying said electrical signals,electronic means activated by said electrical signals or by the absencethereof and operatively connected to the amplifying means, for sensingvariations in the viscosity of the fluid, by said presence or absence ofelectrical signals, as the viscosity changes from one value to anotherpredetermined value, said sensing means being regulated and operativelyconnected to the mined viscosity value is reached.

2. An apparatus useful for measuring the viscosity characteristics of afluid whose viscosity changes under differcut pressure and. temperatureconditions comprising in combination a substantially non-magneticcontainer for the fluid, electromagnetic windings surrounding upper andlowerportions of a cavity in said container for establishing magneticfields in said portions of said container,

means having an appreciable viscous drag and being responsive to saidfields positioned within said cavity and freely movable in the fluid,means for intermittently and regularly electrically energizing each ofsaid windings admin means is caused to move into the resultant magneticfields, surfaces at both the top and bottom of saidcavity which generateand transmit sound waves when struck by said movable means, means forconverting said sound waves into electrical signals, means foramplifying. said electrical signals, means for intermittently energizingonly the upper electromagnetic winding when the viscosity of the fluidis low, means for intermittently energizing both the upper and lowerwindings when the viscosity becomes.

higher, electronic means activated by said electrical signals or by theabsence thereof and operatively connected to the foregoing elementsandmost particularly-with the signal amplifying means and with theenergizing means for the windings for sensing variations in theviscosity of the fluid,- by said presence or absence of electricalsignals, as its viscosity changes successively from a low value to avalue where the forced gravity alone becomes insuflicient to. cause themovable means to strike the lower surface of the cavity during thetimein the. cycle that the upper winding is de-energized, thence to a valuewhere the force exerted by the. upper winding during'the time in thecycle that it is' energized is insufficient to cause the movable meansto strike the upper surface of 'the cavity, and optionally to a valuewhere gravitational force supplemented by the force exertedby the lowerwinding during the time in the cycle that it is energized becomesinsuflicient to cause the movable means to strike the lower surface ofthe cavity, and means responsive to the said sensing means andoperatively connected thereto for recording when the viscosity of thefluid so changes from any'ldwer value to any of said higher values. I

'3-. An apparatus useful for measuring the viscosity characteristics ofa fluid Whose viscosity changes under different pressure and temperatureconditions compris ing in combination a substantially non-magneticcontainer for the fluid,.electromagnetic winding means for establishinga'magnetic field in an upper portion of a cavity in said container,means having an appreciable viscous drag and being responsive to saidfield positioned within said cavity and freely movable in the fluid,means for intermittently and regularly electrically energizingsaidwinding whereby said electromagnetically responsive movable means iscaused during the time said winding is energized to move into theresultant magnetic field and against a surface in the top portion ofsaid cavity which generates and transmits sound waves when struck bysaid movable means, a bottom surface in said cavity which also generatesand transmits sound waves when struck by said movable means, means forconverting said sound waves into electrical signals, means foramplifyingsaid electrical signals, electronic means operativelyconnected to the amplifying means and activated by the amplifiedelectrical signals'or by the absence thereof for sensing variations inthe viscosity of the fluid, by 'saidpresence or absence of electricalsignals, as itchangcs from one value to other higher predeterminedvalues and means responsive to the said sensing means and operativelyconnected thereto for recording when such higher predetermined viscosityvalues I 5. An apparatus according to clair'n 3 wherein a predeterminedviscosity value of the'fluid is reached when the movable means fails tostrike the upper surface of, the cavity during the time in the cyclethat the upper winding is energized.

6. An apparatus according to claim 3 wherein the as paratus is providedwith means for heating the container to any predetermined temperatureand with means for recording the temperature of the fluid in thecontainer.

7. An apparatus according to claim 3 wherein the apparatus is providedwith means for cooling the container to any predetermined temperatureand with means for recording the temperature of the fluid in thecontainer.

8. An apparatus according to claim 3 wherein the apparatus is-providedwitnmeans for pressurizing the interior and the contents of thecontainerand with means for recording the pressure within the'container.

. 9. A process for measuring'the viscosity characteristics of afluidwhose viscosity changes under different pressure and temperatureconditions which comprises: (1)' filling the cavity of asubstantiallynon-magnetic container with the fluid, which cavity is surrounded at itsupper: portion with an electromagnetic winding and which cavity hasdisposed therein and freely movable in the fluid means having anappreciable viscous drag and which is resp'on sive to saidelectromagnetic field, and which cavity also possesses surfaces at itstop" and bottom which generate and transmit sound waves when struck bysaid movable means; (2)'interr r1ittently and regularly electricallyenergiz'ing said winding whereby said electromagnetically responsivemovable means is caused to move upwardly into a the resultant uppermagnetic field through the fluid toward energizinglthe" upper windingwhen the viscosity of the the upper surface of said cavity when saidwinding is energized and, by gravity'when said upper winding isdeenergized to'move' downwardly through the fluid toward the lowersurface of said container; (3) converting sound waves generated at 'bothtop and bottom surfaces whenever such surfaces are struck intoelectrical signals, amplifying same and sending them to an electronicsenser which is responsive to said amplified Signals or to the absenceof same; (4) controlling the temperature and pressure within saidnon-magnetic container to simulate conditions which the fluid mightencounter; and (5 recording by means of a recorder, which isprecalibratcd to measure the viscosity of the fluid'being tested and todo so by being responsive to said electronic senser, when the viscosityof the fluid becomes so greatthat gravitational force becomesinsufficient to cause the movable means to strike the lower surfaceduring the time in the cycle that the upper winding is de-energized andalso when the electromagnetic force exerted by the upper winding becomesinsufficient to cause the'movable means to strike the upper surfaceduring the period in the cycle that the upper winding is energized.

10. A process for measuring the viscosity characteristics of a fluidwhose viscosity changes under different pres sure and temperatureconditions which comprises: 1) filling the cavity of a substantiallynon-magnetic container with the fluid, which cavity is surrounded at itsupper and lower portions with electromagnetic windings and which cavityhas disposed'therein and freely movable in the fluid means having anappreciable viscous drag and which is responsive to said electromagneticfields, and which cavity also possesses surfaces at itstop and bottomwhich gen erate and transmit sound waves when struck by said movablemeans}(2)iintermittently'and regularly electrically fluidis low wherebysaid electro'magnetically responsive movable means is caused to nroveupwardly into the resultant uppermagnetic field through the fluid towardthe upper surface of said cavity when said windingis' energized and', by gravity, when said upper winding is deenergized, to move downwardlythrough the fluid toward the lower surface of said containers; (3)additionally intermittently 7 and regularly electrically energizing thelower winding whenth'evis'cosity of the fluid, becomes so high as toprevent the movable" means'from striking the lower surface by themere'force ofgravity alone during the time portion "er cycle that theupper winding is de-energized; (4) converting the; sounds generated atboth top and bottom stir-magma electrical signals, amplifying same andsendingthem to an electronic sens'cr WhiChiS responsive'to saidamplified signals or to the absence of same; (5) controllingthetemperature and pressure within saidnonby theuiiper winding becomesinsuflicient to cause the. movable means to strike the upper surfaceduring the I period in the cycle that the upper winding is energized;

and optionally when gravitational force plus the electroa magnetic forceexerted by the lower winding are together insufiicient'to cause themovable means to strike the-lower surface during the periodin the cyclethat the lower winding is energized.

11. An apparatus useful for measuring viscosity charracteristics of afluid whose viscosity changes under different pressure and-temperatureconditions comprising in combination: (1) a substantially non-magneticvpressure cell for the fluid, internally threaded near its top; (2)electromagnetic windin'g ineans for establishing a magflanged at itsbase and externally threaded at its upper portion, also possessing ahollow cylindrical bore and" adapted for close proximate insertionthrough the hollow cylindrical bore of said closure (7) a resilientsealing gasket surroundingsaid inlet stem and situated between theflange of said stem and the base of said closure 5;

netic field insaid cell; (3) means having an appreciable r viscous dragand being responsive to said field positioned within said cell andfreely movable in the fluid; (4) means for intermittently and regularlyelectricallyrenergizing said I winding whereby said electromagneticallyresponsive movable. means is caused to move into the resultant magneticfield; (5) a closure possessing a hollow cylindrical bore adapted to bethreaded into said cell; (6) a cylindrical inlet stem flanged at itsbase and externally threaded atits upper portion, also possessingahollow cylindrical bore and adapted for, close proximate insertionthrough the hollow cylindrical bore ofsaid closure 5; (7) a resillentsealing gasket surrounding said inlet -stein and situated between theflange of said stem and the base of said closure 5; .(8) a pressure sealnut adapted to be threaded about said inlet stern and to cause theflange of said stern to'pressure the sealing gasket against the bottomof said elesure'; (9) a valve body threaded onto the top of said inletstem and forming a pressure-tight seal therewith; (10) pressure inputmeans in said valve body communicating with the hollow cylindrical boreof said inlet stem;

(11) a thermowell packing bolt threaded into said valve body forming apressure-tight seal therewith and having a hollow cylindrical boretherein; (12) a thermowell projecting through said packing bolt, saidvalve body and said inlet stem into'said pressure cell; (13) means,opera- 'tively connected to the movement of the viscous drag meanscaused by the electromagnetic winding, for sensing variations in theviscosity of the fluid as it changes from one value'toother values; and(14) means responsive to'the said sensing means and operativelyconnected thereto for recording said varied viscosities. 7

12. An apparatus useful for measuring viscosity characteristics of afluid whose viscosity changes under different pressure'andtemperatureconditions comprising in combination: (1) a substantially non-magneticpressure cell for the fluid, I internally. threaded .near' its top;

, electromagnetic ,winding' means for-establishing a magnetic field insaid cell; (3) meanshaving'an appreciable viscous drag and beingresponsiveto saidfield positioned within said cell and freely movable inthe fluid; (4)

means for intermittently and regularly electrically energizingsaidwinding whereby said electromagnetically responsivc movable means iscaused to'move into the resultant vmagnetic field and toward a surfacein the top portion of said cell ;which generates and transmits soundwaves-when struck by said movable means and "by gravity when saidwinding is not energized toward a bottom (8) a pressure seal nut adaptedto be threaded about said in'let stem and to cause the flange of saidstem to ,(10) pressure input means in said valve body communi-' eatingwith the hollow cylindrical bore of said inlet stem; (11) a thermowellpacking bolt threaded into'said valve body, forming'a pressure-tightseal therewith and having.

a hollow cylindrical bore therein; 12) a thermowell projecting throughsaid packing bolt, said valve body and said inlet stern into saidpressure cell; (13) means for converting the sound waves caused by theimpact of the magnetically responsive means 3- against the top andbottomsurfaces of said cell into electrical signals; (14) means foramplifying said electrical signals; (15) electronic means operativelyconnected to amplifying means and activated by the amplified electricalsignalsor by the absence thereof for sensing variations in the viscosityof the fluid, by said presence or absence of electrical sig nals', asitchanges from one value to other values; and (16) means responsive tothe said sensing means and operatively connected thereto for recordingsaid varied viscosities.

13. An apparatus useful for measuring viscosity characteristics of afluid whose viscosity changes under difiere ent pressure and temperatureconditions comprising in combination: (1) a substantially non-magneticpressure able viscous drag and being responsive to said fieldspositioned within said cell and freely movable in the fluid;- (4) meansfor intermittently and regularly electrically energizing each ofsaidwindings whereby said electromagnetically responsive movable means iscaused to move. into the resultant magnetic fields and toward surfacesin the top and bottom portions of said cell which generate and transmitsound waves when struck by said movable means; (5) a closure possessinga hollow cylindrical bore adapted to be threaded into said cell; (6) acylindrical inlet stern flanged at its base and externally threaded atits upper portion, also possessing a hollow cylindrical bore and adaptedfor close proximate insertion through the hollow cylindrical bore ofsaid closure 5; (7) a resilient sealing gasket surrounding said inletstern and situated between the flange of'said stem and the base of saidclosure 5; (8) a pressure seal nut adapted to be threaded about saidinlet stem and to cause the flange of said stem to pressure the sealinggasket against the bottom of said closure; (9) a valve body threadedonto the top of said inlet stem and forming a pressure-tight sealtherewith; (l0) pressure input means in said 'valve body communir eatingwith the hollow cylindrical bore of said-inlet stem; 7

(1 1) aithermowell packing boltthreaded into said valve body, forming apressure-tight seal therewith andlhaving V convertingthesoundtwavescaused by the impact ofthe surface in said cell which also generates andtransmits sound waves when struck by said movable means; (5) a closurepossessing a hollow cylindrical bore adapted torbe threaded into saidcell; (6) a cylindrical; inlet stem magnetically responsive'means 3against the top and bottom surfaces of said cellinto electrical signals;(14) means for amplifying said electrical signals; (15) eleotronic meansoperatively connected to the amplifying means and activated by theamplified electrical signals or by the absence thereof for sensingvariations in the viscosity of the fluid, by said presence or absence ofelectrical signals, as it changes from one value to other values;

17 and (16) means responsive to the said sensing means and operativelyconnected thereto for recording said varied viscosities. V a

14. An apparatus useful for measuring viscosity characteristics of afluid whose viscosity changes under different pressure and temperatureconditions comprising in combination: (1) a substantially non-magneticpressure cell for the fluid, internally threaded near its top; (2)electromagnetic windings surrounding upper and lower portions of saidcell for establishing magnetic fields in said portions of said cell; (3)means having an appreciable viscous drag and being responsive to saidfield positioned within said cell and freely movable in the fluid; (4)means for intermittently and regularly electrically energizing each ofsaid windings whereby said electromagnetically responsive movable meansis caused to move into the resultant magnetic field and toward surfacesin the top and bottom portions of said cell which generate and transmitsound waves when struck by said movable means; (5) -a closure possessinga hollow cylindrical bore adapted to be threaded into said cell; (6) acylindrical inlet stem flanged at its base and externally threaded atits upper portion, also possessing a hollow cylindrical bore and adaptedfor close proximate insertion through the hollow cylindrical bore ofsaid closure 5; (7) a resilient sealing gasket surrounding said inletstern and situated between the flange of said stern and the base of saidclosure 5; (8) a pressure seal nut adapted to be threaded about saidinlet stem and to cause the flange of said stem to pressure the sealinggasket against the bottom of said closure; (9) a valve body threadedonto the top of said inlet stem and forming a pressure-tight sealtherewith; (10) pressure input means in said valve body communicatingwith the hollow cylindrical bore of said inlet stem; (11) a thermowallpacking bolt threaded into said valve body, forming a pressure-tightseal therewith and having a hollow cylindrical bore therein; (12) athermowall projecting through said packing bolt, said valve body andsaid inlet stem into said pressure cell; (13) means for converting thesound waves caused by the impact of the magnetically responsive means 3against the top and bottom surfaces of said cell into electricalsignals; (14) means for amplifying said electrical signals; (15)electronic means operatively connected to the amplifying means andactivated by the amplified electrical signals or by the absence thereoffor sensing variations in the viscosity of the fluid, by said presenceor absence of electrical signals, as it changes from one value toanother predetermined value; (16) means operatively connected to saidsensing means for intermittently energizing only the upperelectromagnetic winding when the viscosity of the fluid is low; (17)means also operatively connected to said sensing means forintermittently energizing both the upper and lower windings when theviscosity reaches a predetermined higher value; and (18) meansresponsive to the said sensing means and operatively connected theretofor recording said varied viscosities.

15. An apparatus useful for measuring the viscosity characteristics of afluid whose viscosity changes under different pressure and temperatureconditions comprising in combination a substantially non-magneticcontainer for the fluid; electromagnetic winding means for establishinga magnetic field in an upper portion of a cavity in said container;means having an appreciable viscous drag and being responsive to saidfield positioned within said cavity and freely movable in the fluid;means for intermittently and regularly electrically energizing saidwinding whereby said electromagnetically responsive movable means iscaused during the time said winding is energized to move into theresultant magnetic field and against a surface in the top portion ofsaid cavity which generates and transmits sound waves when struck bysaid movable means; means for converting said sound waves intoelectrical signals; means for amplifying said r a t I 18 electricalsignals; electronic means operatively connected to the amplifying meansand activated by the amplified electrical signals or by the absencethereoffor sensing variations in ,theviscosity of the fluid, by saidpresence or absence of electrical signals, as it changes from one valueto other values; and means responsive to the fore-. going sensing meansand operatively connected thereto for recording said varyingviscosities.

16. An apparatus useful for measuring viscosity characteristics of afluid whose viscosity changes under different pressure and temperatureconditions comprising a substantially non-magnetic pressure cell for thefluid, internally threaded near its top; electromagnetic winding meansfor establishing a magnetic field in said cell;-

a bob having an appreciable viscous drag and being responsive to saidfield positioned within said cell and freely movable in the fluid; meansfor intermittently and regularly electrically energizing said windingwhereby said electromagnetically responsive movable bob is caused tomove into the resultant magnetic field; a closure possessing a hollowcylindrical bore adapted to be threaded into said cell; a cylindricalinlet stem flanged at its base and'externally threaded at its upperportion, also possessing a hollow cylindrical bore and adapted for closeproximate insertion through the hollow cylindrical bore of said closure;a resilient sealing gasket surrounding said inlet stem and situatedbetween the flange of said stern and the base of said closure; apressure seal nut adapted to be threaded about said inlet stem and tocause the flange of said stem to pressure the sealing gasket against thebottom of said closure; a valve body threaded onto the top of said inletstem and forming a pressuretight seal therewith; pressure input means insaid valve body communicating with the hollow cylindrical bore of saidinlet stem; a thermowall packing bolt threaded into said valve bodyforming a pressure-tight seal therewith and having a hollow cylindricalbore therein; a thermowell projecting through said packing bolt, saidvalve body and said inlet stem into said pressure cell; a surface at thetop of the cavity of said container which generates and transmits soundwaves when struck by said bob; means for converting said sound wavesinto electrical signals; means for amplifying said electrical signals;electronic means operatively connected to the amplifying means andactivated by the amplified electrical signals or by the absence thereoffor sensing variations in the viscosity of the fluid, by said presenceor absence of electrical signals, as it changes from one value to othervalues; and means responsive to the foregoing sensing means andoperatively connected thereto for recording said varying v1scos1t1es.

17. A process for measuaring the viscosity characteristics of a fluidwhose viscosity changes under dilferent pressure and temperatureconditions which comprises: (1) filling the cavity of a substantiallynon-magnetic container with the fluid, which cavity is surrounded at anupper portion with an electro-magnetic winding means for establishing amagnetic field in said upper portion of the cavity, which cavity, hasdisposed therein and freely movable in the fluid a bob having anappreciable viscous drag and which is responsive to said electromagneticfield, and which cavity also possesses a surface at its top whichgencrates and transmits sound waves when struck by said movable bob; (2)intermittently and regularly electrically energizing said windingwhereby said electromagnetically responsive movable bob is caused duringthe time said winding is energized to move upwardly into the resultantmagnetic field and against said surface in the top portion of saidcavity which generates and transmits sound waves when struck by saidmovable bob; (3) converting said sound waves into electrical signals;(4) amplifying said electrical signals; (5) sending said amplifiedsignals to an electronic senser which is responsive to said amplifiedsignals or to the absence of same and which also senses variations inthe viscosity of the fluid, by said presence 19 or absence of electricalsignals, as it changes from one value to other values; (6) controllingthe temperature and pressure within said non-magnetic container tosimulate conditions which'the fluid might encounter; and -(7) recordingsaid varying viscosities by recorder means responsive to said sensingmeans and operatively connected thereto.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN APPARATUS USEFUL FOR MEASURING THE VISCOSITY CHARACTERISTICS OF AFLUID WHOSE VISCOSITY CHANGES UNDER DIFFERENT PRESSURE AND TEMPERATURECONDITIONS COMPRISING IN COMBINATION A SUBSTANTIALLY NON-MAGNETICCONTAINER FOR THE FLUID, ELECTROMAGNETIC WINDINGS SURROUNDING UPPER ANDLOWER PORTIONS OF A CAVITY IN SAID CONTAINER FOR ESTABLISHING MAGNETICFIELDS IN SAID PORTIONS OF SAID CONTAINER, MEANS HAVING AN APPRECIABLEVISCOUS DRAG AND BEING RESPONSIVE TO SAID FIELDS POSITIONED WITHIN SAIDCAVITY AND FREELY MOVABLE IN THE FLUID, MEANS FOR INTERMITTENTLY ANDREGULARLY ELECTRICALLY ENERGIZING EACH OF SAID WINDINGS WHEREBY SAIDELECTROMAGNETICALLY RESPONSIVE MOVABLE MEANS IS CAUSED TO MOVE INTO THERESULTANT MAGNETIC FIELDS SURFACES AT BOTH THE TOP AND BOTTOM OF THECAVITY OF SAID CONTAINER WHICH GENERATE AND TRANSMIT SOUND WAVES WHENSTRUCK BY SAID MOVABLE MEANS, MEANS FOR CONVERTING SAID SOUND WAVES INTOELECTRICAL SIGNALS, MEANS FOR AMPLIFYING SAID ELECTRICAL SIGNALS,ELECTRONIC MEANS ACTIVATED BY SAID ELECTRICAL SIGNALS OR BY THE ABSENCETHEREOF AND OPERATIVELY CONNECTED TO THE AMPLIFYING MEANS, FOR SENSINGVARIATIONS IN THE VISCOSITY OF THE FLUID, BY SAID PRESENCE OR ABSENCE OFELECTRICAL SIGNALS, AS THE VISCOSITY CHANGES FROM ONE VALUE TO ANOTHERPREDETERMINED VALUE, SAID SENSING MEANS BEING REGULATED AND OPERATIVELYCONNECTED TO THE INTERMITTENTLY ENERGIZING MEANS SO THAT ONLY THE UPPERELECTROMAGNETIC WINDING IS INTERMITTENTLY ENERGIZED WHEN THE VISCOSITYOF THE FLUID IS LOW, AND BOTH THE UPPER AND LOWER WINDINGS AREINTERMITTENTLY ENERGIZED WHEN THE VISCOSITY REACHES A PREDETERMINEDHIGHER VALUE, AND MEANS RESPONSIVE TO THE SAID SENSING MEANS ANDOPERATIVELY CONNECTED THERETO FOR RECORDING WHEN THE HIGHERPREDETERMINED VISCOSITY VALUE IS REACHED.